Auto Tech

The Turbocharged direct injection or TDI is a design of turbo diesel engines that feature turbocharging and cylinder-direct fuel injection. This technology is proudly developed and produced by the Volkswagen Group. The TDI engine uses direct injection where a fuel injector sprays atomized fuel directly into the main combustion chamber of each cylinder rather than the pre-combustion chamber prevalent in older diesels which used indirect injection.

The engine also uses forced induction by way of a turbocharger to increase the amount of air which is able to enter the engine cylinders, and most TDI engines also feature an intercooler to lower the temperature (and therefore increase the density of the 'charged', or compressed air from the turbo, thereby increasing the amount of fuel that can be injected and combusted. These, in combination, allow for greater engine efficiency, and therefore greater power outputs (from a more complete combustion process compared to indirect injection), while also decreasing emissions and providing more torque than its non-turbo and non-direct injection petrol engine counterpart.

Similar technology has been used by other automotive companies, but "TDI" specifically refers to these Volkswagen Group engines. The reduced material volume of the direct injection diesel engine reduces heat losses, and thereby increases engine efficiency, at the expense of slightly increased combustion noise. A direct injection engine is also easier to start when cold, due to more efficient placing and usage of glow plugs.

TDI engines are currently available in the following models:

- Polo Sedan 1.6 TDI M/T

- Jetta 2.0 TDI M/T

- Tiguan 2.0 TDI A/T

- Touran 2.0 TDI DSG

- Touareg 3.0 TDI V6 A/T